JP2010220273A - Motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control device for driving an AC motor, capable of generating an optional level of sound without changing the structure of the AC motor and a switching frequency of the motor control device even under all the operation conditions or load conditions. <P>SOLUTION: The motor control device for driving the AC motor causes the AC motor to generate an optional level of sound by superimposing harmonics of an optional frequency over a current of a component not involved in torque generation of the motor. Also, torque vibration due to the superimposed harmonics is prevented by employing a configuration in which the superimposed harmonic current has no effect on a current component involved in the torque generation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to motor control, and more particularly to control of generated noise.

  As an example of the motor control device based on the prior art, a case where a surface permanent magnet type synchronous motor is driven is shown in FIGS. 6 and 7, and the prior art will be described based on these drawings.

  The electric motor 1 is a surface permanent magnet type synchronous electric motor, and a rotation angle detector 2 for detecting the rotation angle θ of the electric motor 1 is installed. The current detector 3 detects three-phase currents iU, iV, iW flowing through the electric motor. The current control device 4 inputs the torque command τ *, the three-phase currents iU, iV, iW, and the rotation angle θ, and outputs the three-phase voltage commands VU *, VV *, VW *. The inverter device 5 receives three-phase voltage commands VU *, VV *, and VW *, and outputs three-phase voltages VU, VV, and VW that are equivalent to VU *, VV *, and VW *, and outputs the motor 1 Apply to.

  A schematic representation of the electric motor 1 is shown in FIG. 3, and a three-phase current flows. In terms of control, the direction of the magnet magnetic flux is d-axis, and the direction perpendicular to the d-axis is q-axis, as shown in FIG. Consider the coordinates synchronized with the rotor.

  Next, the current control device 4 will be described with reference to FIG. The current command converter 41 receives the torque command τ * and outputs a q-axis current command iq * that is a current value when the torque command τ * is generated. The current coordinate converter 42 converts the three-phase currents iU, iV, iW into a d-axis current id and a q-axis current iq, which are currents on the d-axis and q-axis, based on the rotor angle θ. The q-axis current controller 43 outputs a q-axis voltage command Vq * so that the difference between the q-axis current command iq * and the q-axis current iq becomes zero. The d-axis current controller 44 outputs a d-axis voltage command Vd * so that the d-axis current id becomes zero. The voltage command coordinate converter 45 converts the d-axis voltage command Vd * and the q-axis voltage command Vq * into three-phase voltage commands VU *, VV *, and VW * based on the rotor angle θ.

  Next, the inverter device 5 will be described with reference to FIG. Although the conversion from the U-phase voltage command VU * to the U-phase voltage VU will be described here, the same operation is performed in the V-phase and the W-phase. The U-phase voltage command VU * has a sine wave shape as shown by the curve in FIG. However, since it is difficult to actually output a sinusoidal voltage, the voltage equivalent to the voltage command VU * is switched by switching the maximum voltage and the minimum voltage and changing the time ratio as shown in FIG. Outputs VU.

  Further, without using the rotation angle detector 2, the rotation angle θ of the electric motor 1 may be estimated using the three-phase voltage commands VU *, VV *, VW * and the three-phase currents iU, iV, iW. (For example, patent document 1).

JP 2002-112600 A

  Noise is generated when the electric motor 1 is driven. Examples of noise sources include those caused by the mechanical structure of the electric motor 1 and those caused by electromagnetic force caused by flowing current.

  As a result of the mechanical structure, there is noise caused by the cooling device or the bearing portion of the electric motor 1. The frequency of these noises depends on the motor speed and structure.

  Noise caused by the electromagnetic force becomes noise when the electric motor 1 vibrates due to the electromagnetic force. This noise frequency depends on the current frequency and on the inverter 5 switching frequency.

  Noise that depends on the rotational speed of the electric motor 1 and the frequency of the current cannot be changed once the operating conditions such as the rotational speed and the load state are determined. Although the noise can be changed by changing the structure of the electric motor 1, the mechanical structure is determined under various constraints, and thus cannot be easily changed due to the noise change. Moreover, it is difficult to change the mechanical structure of the electric motor 1 once made, and in particular, it is impossible to change it during operation.

  Regarding noise that depends on the switching frequency of the inverter 5, the noise can be changed by changing the switching frequency or the switching waveform. However, changing the switching frequency and the switching waveform causes a change in control characteristics and a loss due to switching of the inverter 5, and in most cases it cannot be easily changed. For example, when the switching frequency is lowered, the control period is prolonged, so that the control performance is lowered. In addition, since the distortion of the voltage waveform increases, current harmonics increase and torque pulsation of the electric motor 1 increases. On the other hand, when the switching frequency is increased, the loss of the inverter 5 increases, leading to an increase in the size of the cooling device.

  That is, the sound generated when the motor is driven once is determined by the design and the operating state. In particular, it can be said that it is difficult to arbitrarily change the generated sound during driving.

  According to the first aspect of the present invention, in the motor control device for driving the AC motor, a sound of an arbitrary height can be obtained by superimposing harmonics of an arbitrary frequency on the current of the component not involved in the torque generation of the AC motor. Is generated from the AC motor.

  According to a second aspect of the present invention, in the electric motor control apparatus according to the first aspect, the motor control apparatus is configured such that the superimposed harmonic current does not affect a current component involved in torque generation.

  It is possible to generate sound having an arbitrary frequency without changing the structure, operating conditions, and switching frequency of the electric motor.

It is an example of the block diagram of the current controller of invention of Claim 1 of this invention. It is an example of the block diagram of the current controller of invention of Claim 2 of this invention. It is a schematic diagram of a structure of a surface type permanent magnet type | mold synchronous motor. It is a schematic diagram of a structure of a surface type permanent magnet type | mold synchronous motor. It is a figure explaining operation | movement of an inverter apparatus. It is an example of the motor control apparatus structure by a prior art example. It is an example of the block diagram of the current control apparatus by a prior art example.

  Exemplary embodiments of an electric motor control device according to the present invention will be described below in detail with reference to the drawings.

  An embodiment of the invention of claim 1 will be described with reference to FIG. 1, but the same parts as those of the prior art will be omitted.

  The d-axis current command generator 46 receives the generated sound frequency command fs * and outputs a d-axis current command id * having the frequency vibration component. The d-axis current controller 44 outputs the d-axis voltage output Vd * so that the difference between the d-axis current command id * and the d-axis current id becomes zero.

  With this configuration, the vibration of the generated sound frequency command is superimposed on the d-axis current id.

  The effect of d-axis and q-axis current will be considered with reference to FIG. When the q-axis current iq flows, one pole of the permanent magnet constituting the rotor of the electric motor 1 is attracted and the other is repelled, so that torque is generated so that the rotor of the electric motor 1 rotates. On the other hand, when the d-axis current id flows, an electromagnetic force is generated in which the opposing permanent magnet poles are attracted or repelled. However, since the magnet poles and the d-axis are in the same direction, there is no rotational torque. That is, no torque is generated by the d-axis current id, but an electromagnetic force that attracts or repels the rotor and the stator of the electric motor 1 is generated.

  Therefore, when the vibration of the generated sound frequency command fs * is superimposed on the d-axis current id, the electromagnetic force between the rotor and the stator of the motor 1 changes at the frequency of the generated sound frequency command fs *, and the motor 1 itself is Since it vibrates, it becomes possible to generate a sound corresponding to the generated sound frequency command fs * from the electric motor 1.

  At this time, the generated sound frequency command fs * can be freely selected without being restricted by operating conditions or the structure of the electric motor 1. Further, it can be freely changed even during driving.

  The invention of claim 2 will be described with reference to FIG. 2, but the same parts as those of the first embodiment will be omitted.

  The differentiator 47 outputs the rotation angular velocity ω by differentiating the rotation angle θ. The d-axis non-interference compensator 48 receives the q-axis current iq and outputs a value obtained by multiplying the rotational angular velocity ω by the inductance L of the motor coil. The q-axis non-interference compensator 49 receives the d-axis current id and sums the value obtained by multiplying the rotor angular velocity ω by the inductance L of the motor coil, and the value obtained by multiplying the rotor angular velocity ω and the flux linkage number φ by the permanent magnet. Is output.

  The q-axis voltage command Vq * is obtained by adding the output of the q-axis non-interference compensator 49 to the output of the q-axis current controller 43. The d-axis voltage command Vd * is obtained by subtracting the d-axis non-interference compensator 48 from the output of the d-axis current controller 44.

  It is known that the relationship between the voltage and current of the surface permanent magnet type synchronous motor is the relationship of [Equation 1].

[Equation 1]
Vd = (R + p · L) id−ω · L · iq (Expression 1)
Vq = ω · L · id + (R + p · L) iq + ωφ (2nd formula)

  Here, R is the resistance value of the coil of the motor 1, L is the inductance value of the motor 1, p is a differential operator, and φ is the number of magnetic flux linkages by the permanent magnet of the motor 1.

  Paying attention to the second equation of [0030], it can be seen that the influence of the d-axis current id acts on the relationship between Vq and iq. That is, when a harmonic flows in the d-axis current id, it affects the current control of the q-axis current iq, and thus a harmonic may flow in the q-axis current iq. When harmonics flow in the q-axis current iq, it is not desirable because it causes torque vibration.

  Thus, the d-axis non-interference compensator 48 cancels the influence of the second term on the right side of the first expression in [0030], and the first term on the right side of the second expression is canceled by the q-axis non-interference compensator 49. It is possible to prevent the id harmonic from interfering with the q-axis current iq, and the generated sound can be controlled to an arbitrary sound in a state where desired control characteristics are obtained without generating torque vibration or the like.

  According to the present invention, it is possible to freely control the sound generated from the motor without changing the operating conditions, the structure of the motor, and the switching frequency. Moreover, since this method can be applied to an existing motor control device, it is extremely effective.

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Rotation angle detector 3 Current detector 4 Current control device 41 Current command converter 42 Current coordinate converter 43 q-axis current controller 44 d-axis current controller 45 Voltage command coordinate converter 46 d-axis current command generator 47 Differentiator 48 d-axis non-interference compensator 49 q-axis non-interference compensator 5 Inverter device

Claims (2)

  In the motor control device for driving an AC motor, generating a sound of an arbitrary height from the AC motor by superimposing a harmonic of an arbitrary frequency on a current of a component not involved in torque generation of the AC motor. An electric motor control device.   The motor control device according to claim 1, wherein the superposed harmonic current does not affect a current component related to torque generation.

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